Linear drive

Abstract

The invention relates to a linear drive comprising at least one first drive element (2) having a first end (3) and a second end (4) in a longitudinal direction (L), wherein the first drive element (2) has a main body (5) with a rear side and with a drive side opposite same in a vertical direction and having a plurality of teeth (6), wherein the teeth (6) are aligned over a width (B) of the first drive element (2), wherein the teeth (6) are spaced apart from one another in a tooth distribution (T) in the longitudinal direction (L), wherein the first drive element (2) has a holder (8) on which the main body (5) of the first drive element (2) is arranged with its rear side. The linear drive has at least one second driveable drive element (16) having teeth (6), wherein at least one tooth (6) of the second drive element (16) engages in at least one tooth gap (11) of the first drive element (2), whereby the second drive element (16) can be rolled on the first drive element (2). The first drive element (2) can be non-destructively removed from the holder (8).

Description

[0001] The invention relates to a linear drive according to the preamble of claim 1. State of the art

[0002] Linear drives are known from the prior art and are used particularly and frequently in industrial mechanical engineering. DE 10 2007 006 951 A1 discloses an exemplary embodiment of a linear drive.

[0003] GB 1 424 477 A also shows an example of a linear actuator.

[0004] A popular design for drive systems for reversing linear motion involves combining two corresponding drive elements. The first drive element is stationary, while the second drive element engages with the first and can move linearly along it. A typical combination of drive elements is a rack and pinion. The pinion is usually connected to the shaft of a drive motor and is stationary. On the output side, the pinion engages with the rack of a linearly moving slide, so that the rotational motion of the pinion is transferred to the rack, allowing the slide to be moved linearly or translationally by means of the rack.

[0005] Conversely, the motor can be connected to the carriage. In this case, as described previously, the motor is connected to the rack via a gear, with the rack being stationary. The carriage thus has its own drive, allowing it to be moved linearly along the stationary rack by the rotational movement of the gear.

[0006] However, it proves problematic that manufacturing tolerances can lead to pitch errors between the corresponding drive elements, which can cause interference during operation. Due to the rigid gearing of the drive elements, which are usually made of metallic materials, pitch errors result in high gear wear and consequently significant noise generation.

[0007] Another possible combination of drive elements is a linear drive unit with two meshing drive belts. A static drive belt is open and elongated, fixed and either permanently or very difficult to detach, from a rail, for example, an aluminum rail. In other words, the static drive belt acts as a rack and pinion. A second drive belt, movable relative to the static drive belt, is guided over a motor drive shaft or a gear connected to the drive shaft and around additional pulleys. The drive unit with the second drive belt is connected to a movable carriage, allowing the carriage to move linearly along the static drive belt. In other words, the movable drive belt acts as a gear. This can also be reversed, as previously described using gears and racks.

[0008] A disadvantage is that the static drive belt of the rack cannot be separated from the rail and replaced separately, or only with great difficulty, when it reaches its wear limit. This increases the effort and costs associated with replacing the static drive belt due to wear, as the rail either has to be replaced together with the drive belt, which can lead to increased costs, or it can only be separated from the drive belt with great difficulty, which increases the replacement time and thus can lead to longer machine or system downtime.

[0009] Well-known applications of the linear drives described above include, for example, conveyor or storage technology in lifting or storage and retrieval machines. Task

[0010] The invention is based on the objective of providing a linear drive with a drive belt as a rack and pinion, which is capable of compensating for any pitch errors between the corresponding drive elements. Preferably, the linear drive should also have a maintenance-friendly design, allowing for simple and cost-effective replacement of wear-prone components. Solution to the task

[0011] The solution to this problem is achieved by a linear drive with the features of the main claim.

[0012] Further advantageous training opportunities are revealed in the dependent claims. Advantages of the invention

[0013] The linear drive disclosed in claim 1 comprises at least one first drive element having a first end and a second end in the longitudinal direction. The first drive element has a base body with a back side and a drive side opposite the back side in a vertical direction, the drive side having a plurality of teeth, wherein the teeth are oriented transversely to the longitudinal direction over a width of the first drive element and are spaced apart from each other in a tooth pitch in the longitudinal direction.

[0014] The first drive element has a bracket to which the base body of the first drive element is attached with its rear side. The bracket can be made of metal, preferably aluminum, and is designed to stiffen the base body.

[0015] The linear drive has at least one second, toothed, driveable element, wherein at least one tooth of the second drive element engages in at least one tooth gap of the first drive element. The second drive element can thus roll on the first drive element, and the first drive element can be detached from the holder without damage.

[0016] The linear drive is characterized in that the base body and the holder can be connected with at least one U-bolt, wherein the U-bolt at least partially replaces a tooth of the first drive element, or the base body and the holder can be joined together with a hook and loop fastener having two straps, wherein a strap of the hook and loop fastener is arranged on the base body on the side opposite the teeth and on the side of the holder associated with the base body.

[0017] In other words, the base body of the first drive element of the linear drive according to the invention can have a toothed belt made of polymeric material. To stiffen the flexible toothed belt and to prevent lateral migration of the toothed belt, a holder is arranged on the back of the toothed belt. The toothed belt and the holder can be connected to each other via a detachable connection, for example, a clamp connection or a hook-and-loop fastener. This provides a detachable connection between the base body of the first drive element and the holder, which, for example, allows the base body to be replaced due to wear without having to replace the holder itself.

[0018] The main body and teeth can be made of a polymeric material or at least partially consist of one. The polymeric material of the main body and teeth dampens vibrations in the linear drive and reduces noise. Various elastomers based on vulcanizable rubber compounds, comprising at least one rubber component (e.g., EPM, EPDM, HNBR, FKM) as well as compound ingredients, and various polyurethane formulations can be used as polymeric materials. Polyurethane is particularly well-suited as a base material for timing belts due to its exceptional wear resistance and resistance to greases and oils, making it ideal for use in highly stressed drives.

[0019] The linear drive can, for example, include a gear connected to the output shaft of a motor as its second drive element. At least one tooth of this gear engages a tooth gap in the first drive element. The motor and any components rigidly connected to it can be moved linearly along the first drive element by the driven gear, reaching any desired position along its length. The polymeric material of the base and teeth of the first drive element, particularly when engaged with a gear made of a metallic material as the second drive element, can dampen vibrations and reduce noise in the linear drive. In another embodiment, the second drive element can also be designed as a toothed belt, which is driven and can roll on the first drive element.It proves particularly advantageous that the force can be transmitted via several meshing teeth, thereby reducing wear on the first and / or second drive element. Depending on the application, the linear drive can have multiple versions of the first and / or second drive element.

[0020] According to another aspect, the base body has a textile coating on the drive side of the surface, which advantageously protects the polymeric material from wear. The textile coating can be made of a knitted or woven fabric of warp and weft threads and can be treated or coated with additives, for example, to reduce the coefficient of friction.

[0021] According to another aspect, longitudinally extending tension members are arranged within the base body and at least partially enclosed by the polymer material. This imparts additional longitudinal stiffness to the flexible base body. Tensile forces can also be transmitted longitudinally by the tension members. This prevents elongation of the base body under load and the resulting change in tooth pitch, which in turn can lead to interference between the first drive element and a second drive element.

[0022] According to the invention, the base body and the mounting bracket can be connected with at least one U-bolt. This provides a detachable connection between the base body of the first drive element and the mounting bracket, which, for example, allows for the replacement of the base body due to wear. The U-bolt can, for example, pass through recesses in the base body. In a further embodiment, the U-bolt can grip the base body on its outer surfaces and clamp it to the mounting bracket.

[0023] According to a further advantageous aspect of the linear drive according to the invention, several U-bolts are spaced apart from each other in the longitudinal direction of the first drive element. This ensures sufficient fixation of the base body of the first drive element to the mounting even over long lengths.

[0024] According to a further advantageous aspect of the linear drive according to the invention, the distance between the U-bolts in the longitudinal direction of the first drive element corresponds to half the predetermined length of the section of the drive that engages with the second drive element. This distance minimizes the number of U-bolts that may be in contact with the second drive element, thereby reducing wear on the second drive element. Since the U-bolts do not serve to transmit power between the first and second drive elements, the described distance between the U-bolts only slightly restricts the power transmission capacity of the linear drive, while at the same time ensuring sufficient fixation of the base body of the first drive element to the mounting.

[0025] According to a further advantageous aspect of the linear drive according to the invention, the distance between the U-bolts in the longitudinal direction of the first drive element corresponds to an integer multiple of the tooth pitch of the first drive element. This ensures that the U-bolts are spaced uniformly apart.

[0026] According to the invention, the at least one U-bolt at least partially replaces a tooth of the first drive element. The U-bolt is preferably made of a metallic material. In other words, the position of the U-bolt corresponds to the position of a tooth. The tooth can be omitted at the position of the U-bolt or subsequently removed. The tension members remain enclosed by the polymeric material of the base body. The U-bolt can be countersunk in the area of ​​the omitted tooth of the first drive element in a plane with the tooth root of the remaining teeth, so that the teeth of the second drive element contact the U-bolt with the smallest possible area, thereby minimizing wear on the teeth of the second drive element. The tooth root is understood to be the area of ​​the tooth where the tooth terminates in the base body.

[0027] According to a further advantageous aspect of the linear drive according to the invention, each U-bolt extends at least partially across the width of the first drive element, with the clamping area of ​​the U-bolt encompassing at least 2 / 3 of the tension members. This ensures sufficient fixation of the bracket to the base body of the first drive element. In a particularly preferred manner, four U-bolts are arranged across the width of the first drive element.

[0028] According to a further advantageous aspect of the linear drive according to the invention, the U-bolt passes through the base body in at least one recess extending from the drive side to the rear side. In other words, the U-bolt is guided through the base body from the drive side to the rear side through at least one recess, for example in the form of a bore. Analogous to the base body, the holder can have recesses of the same number and geometry, so that the U-bolt can pass through the holder as well as the base body. The U-bolt can be guided through the recesses longitudinally and across its width in the transverse direction.In the extension direction of the recess, i.e. in the vertical direction, perpendicular to the longitudinal direction and perpendicular to the transverse direction, the U-bolt can be fixed in such a way that the U-bolt together with the base body is tightened against the bracket, for example by means of a nut.

[0029] According to a further advantageous aspect of the linear drive according to the invention, at least one recess is arranged between two tension members. In this way, the base body can retain its performance or tensile strength despite the recess.

[0030] According to the invention, the base body and the holder can be joined together with a hook and loop fastener having two straps, wherein a strap of the hook and loop fastener is arranged on the base body on the side opposite the teeth and on the side of the holder associated with the base body.

[0031] In other words, the base of the first drive element can be joined to the bracket via a detachable hook-and-loop fastener. The fastener has two interlocking strips: one with loops and the other with barbs that engage in the loops of the first strip. One strip is assigned to the bracket and the other to the base. This provides a detachable connection between the first drive element and the bracket, allowing, for example, the replacement of the first drive element due to wear without having to replace the bracket itself.

[0032] According to a further advantageous aspect of the linear drive according to the invention, the respective belt is bonded to the base body and / or the holder via an adhesive layer. Adhesives for various material combinations are widely available on the market, so that bonding the belts between the polymeric material of the base body and the holder can be implemented cost-effectively.

[0033] According to a further advantageous aspect of the linear drive according to the invention, the belt associated with the base body is materially bonded to the base body during the manufacturing process of the polymer base body. For example, the belt can be inserted into the base body during the extrusion process of the first drive element, so that a materially bond can form between the base body and the belt after the polymer material has cooled.

[0034] According to a further advantageous aspect of the linear drive according to the invention, the first drive element is designed as a toothed belt, wherein the support is designed to stiffen the base body.

[0035] To stiffen the flexible timing belt and prevent lateral movement, a support is mounted on its back. When using a timing belt as the primary component of the first drive element, it is particularly advantageous that timing belts are available in any length and, especially as predefined length sections, can be easily adapted to customer requirements by cutting the timing belt to a multiple of the tooth pitch. Explanation of figures

[0036] An embodiment of the invention will be explained in more detail below with reference to the drawings. Fig. 1shows a toothed belt according to the invention as part of a first drive element with a holder attached via a Velcro fastener in a sectional view. Fig. 2 shows the engagement of the first drive element and the second drive element using the example of two toothed belts. Fig. 3 shows a basic body of a first drive element with recesses provided therein. Fig. 4 shows a toothed belt according to the invention as part of a first drive element with a holder attached via a U-bolt in a sectional view.

[0037] The above figures are described in Cartesian coordinates with a longitudinal direction L, a transverse direction B perpendicular to the longitudinal direction L, and a vertical direction perpendicular to both the longitudinal direction L and the transverse direction B. The longitudinal direction L can also be referred to as depth L, the transverse direction B as width B, and the vertical direction as height. The longitudinal direction L and the transverse direction B together form the horizontal L, B, which can also be referred to as the horizontal plane L, B.

[0038] Fig. 1Figure 1 shows a timing belt as part of a first drive element 2 with a holder 8 attached via a hook-and-loop fastener 15. The holder 8 can be designed as a metal profile. The timing belt has a predetermined length with a first end 3 and a second end 4. The base body 5 and teeth 6 are made of polyurethane. Tension members 10 made of steel, running parallel to each other in the longitudinal direction L of the timing belt, are embedded in the polyurethane of the base body 5. The side of the timing belt with the teeth 6, which are evenly spaced from each other with a tooth pitch T, can also be referred to as the drive side 7. To protect the base body 5 and the teeth 6 from wear, the drive side 7 is coated with a textile covering 9. The coefficient of friction of the drive side 7 of the drive belt can be adjusted via the textile covering in combination with other preparations, such as a Teflon coating.To stiffen the flexible drive belt, a bracket 8 is arranged on the side opposite the drive side 7. This bracket is connected to the drive belt's base body 5 via a hook-and-loop fastener 15. The hook-and-loop fastener 15 has a band 13 associated with the base body 5 and a band 14 associated with the bracket 8. The bands 13 and 14 interact to form the hook-and-loop fastener 15, with the hooks of one band 13, 14 connecting to the loops of the other band 14. The hook-and-loop connection is detachable, allowing for easy replacement of the base body 5 without requiring the bracket 8 to be replaced. The base body 5, together with the attached bracket 8, forms a first drive element 2, which, in conjunction with another drive element, is part of a linear drive.

[0039] Fig. 2Figure 1 shows the engagement of the first drive element 2 and the second drive element 16 using the example of two toothed belts. The drive elements 2 and 16 are part of a linear drive. The first drive element 2 is, for example, fixed to a machine frame, while the second drive element 16, which is driven by a motor, engages the tooth gaps 11 of the first drive element 2 with its teeth 6. The second drive element 16 can roll on the first drive element 2 and is thus linearly movable in the longitudinal direction L along the first drive element 2. The simultaneous engagement of several teeth 6 of the first and second drive elements 2 and 16 avoids local stress peaks, as the force is transmitted evenly across a large number of teeth.

[0040] Fig. 3Figure 1 shows the base body 5 of the first drive element 2, which has a length L and a width B. The elastomeric base body 5 has several recesses 18. Between each pair of recesses 18, which are arranged across the width B of a tooth 6 and form a common pair of recesses 18, the respective tooth 6 is removed. The elastomeric material is removed to such an extent that only a thin layer of the elastomeric material remains to protect the underlying tension members. The recesses 18 extend vertically from the drive side 7 through the base body 5 to the back side and are designed as holes, which can be formed, for example, by drilling or punching. The recesses 18 run in an area between two tension members, so that the tension members are not damaged and can continue to transmit tensile forces without restriction.In addition to the described recesses 18, further recesses 18 are provided in the longitudinal direction L offset over the width B of an adjacent tooth 6, with each pair of recesses 18 forming a common pair of recesses 18. The respective pair of recesses 18 is shifted to the left or right over the width B relative to the pair of recesses 18 of the adjacent tooth 6 by the distance between the recesses 18 assigned to each other.

[0041] Fig. 4Figure 1 shows a toothed belt as part of a first drive element 2 with a bracket 8 attached via a U-bolt 17 in a sectional view. The toothed belt has a predetermined length with a first end 3 and a second end 4. The base body 5 and teeth 6 are made of polyurethane. Steel tension members running parallel to each other in the longitudinal direction L of the toothed belt are embedded in the polyurethane of the base body 5. The side of the toothed belt with the teeth 6, which are evenly spaced from each other with a tooth pitch T, can also be referred to as the drive side 7. To protect the base body 5 and the teeth 6 from wear, the drive side 7 is coated with a textile layer 9. The coefficient of friction of the drive side 7 of the drive belt can be adjusted via the textile layer in combination with other preparations, such as a Teflon coating.To stiffen the flexible drive belt, a bracket 8 is arranged on the side opposite the drive side 7. This bracket is connected to the drive belt's main body 5 via a U-bolt 17 and a nut 19. The U-bolt 17 is inserted vertically from the drive side 7 through the recess 18 in the main body 5 and the bracket 8 to form a clamping connection between the main body 5 and the bracket 8. The recess 18 runs between two adjacent tension members extending longitudinally L. On the drive side 7, the U-bolt 17 is positioned in the recess 18 such that it does not protrude from the tooth gap 11 of the main body 5. A portion of the U-bolt 17 protruding from the bracket 8 is externally threaded, allowing it to be tightened against the bracket 8 with a nut 19, thus creating a clamping connection between the main body 5 and the bracket 8.The clamping connection is detachable, so that if the base body 5 wears out, it can be easily replaced without having to renew the bracket 8. The base body 5, together with the attached bracket 8, forms a first drive element 2, which, in conjunction with another drive element, is part of a linear drive. Reference symbol list (part of the description)

[0042] 2 First drive element 3 First end 4 Second end 5 Base body 6 Tooth 7 Drive side 8 Bracket 9 Textile pad 10 Tension member 11 Tooth gap 13 Band associated with base body 14 Band associated with bracket 15 Hook and loop fastener 16 Second drive element 17 U-bolt 18 Recess 19 Nut B Width / Transverse direction L Longitudinal direction T Tooth pitch

Claims

1. Linear actuator,comprising at least one first drive member (2) having a first end (3) and a second end (4) in the longitudinal direction (L), wherein the first drive member (2) has a base body (5) with a back side and with a drive side (7) opposite in a vertical direction with a plurality of teeth (6), wherein the teeth (6) are aligned over a width (W) of the first drive member (2),wherein the teeth (6) are spaced out to each other in a tooth pitch (T) in the longitudinal direction (L), wherein the first drive element (2) has a bracket (8) on which the base body (5) of the first drive element (2) is arranged with its back side, wherein the linear drive has at least a second, has teeth (6), wherein at least one tooth (6) of the second drive element (16) engages in at least one tooth gap (11) of the first drive element (2), whereby the second drive element (16) can be rolled on the first drive element (2), wherein the first drive element (2) can be detached from the bracket (8) in a non-destructive manner, characterized in that the base body (5) as well as the bracket (8) can be connected with at least one U-bolt screw (17), wherein the U-bolt (17) replaces at least partially one tooth (6) of the first drive element (2) or the base body (5) and the bracket (8) can be joined together with a Velcro fastener (15) comprising two straps (13, 14), whereby on the base body (5) on the opposite side of the teeth (6) and on the side of the bracket (8) assigned to the base body (5) each a band (13, 14) of the Velcro fastener (15).

2. Linear actuator according to claim 1, characterized in that the base body (5) on the drive side (7) has a textile coating (9) on the surface, wherein the textile coating (9) protects a polymer material from wear.

3. Linear actuator according to one of the preceding claims, characterized in that in the base body (5) tension members (10) are arranged in the longitudinal direction (L) and are at least partially enclosed by the polymer material,4. Linear actuator according to any of the preceding claims, characterized in that several U-bolts (17) are spaced from each other in the longitudinal direction (L) of the first drive element (2).

5. Linear actuator according to any of the preceding claims, characterized in that the distance of the U-bolts (17) to each other in the longitudinal direction (L) of the first drive member (2) corresponds to half of the predetermined length of the length portion engaged with the second drive member (16).

6. Linear actuator according to one of the preceding claims, characterized in that the distance of the U-bolts (17) in the longitudinal direction (L) of the first drive member (2) to each other corresponds to an integer multiple of the tooth pitch (T) of the first drive element (2).

7. Linear actuator according to any of the preceding claims, characterized in that each U-bolt (17) extends at least partially over the width (B) of the first drive member (2), wherein the clamping area of the U-bolt (17) comprises at least 2 / 3 of the tension members (10).

8. Linear actuator according to one of the preceding claims, characterized in that the U-bolt (17) engages the base body (5) in at least one recess (18) extending from the drive side (7) to the back side.

9. Linear actuator according to any of the preceding claims, characterized in that at least one recess (18) is arranged between two tension members (10).

10. Linear actuator according to any one of claims 1 to 3, characterized in that the respective tape (13, 14) is connected to the base body (5) and / or the bracket (8) via an adhesive layer.

11. Linear actuator according to claim 10, characterized in that the strip (13) assigned to the base body (5) is materially bonded to the base body (5) by the manufacturing process of the polymer base body (5).

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